Method of working copper.



F. S. CARVER & W.,H. HARMAN.

METHOD OF WORKING COPPER.

APPLICATION FILED SEPT. 2|, 1916.

1 1 2 2, Patented Feb. 20, 1917.

Lsubjected to a combined compression and FRED s. CARVER, or NEWARK, NnwJEnsEY, AND WILLIAM H. Ham/tamer LaNsnowNE, PENNSYLVANIA.

METHOD 0]? WORKING COPPER.

release.

Specification of Letters Patent.

Patented Feb. ao', tart.

Application filed September 21, 1916. Serial No. 121,448.

To all whom it may concern."

Be it known that we, FRED S. CARVER and WILLIAM H. HARMAN, citizens ofthe United States, and residents of Newark, county of Essex, and Stateof New Jersey, and Lansdowne, county of Delaware, and State ofPennsylvania, respectively, have invented certain new' and usefulImprove ments in Methods of Working Copper, of which the following is aspecification.

This invention relates to an improved method of making copper tubes andrifling bands for ordnance.

The methodfis designed to provide such tubes and bands cut therefromwith com paratively littleexpense, that are solid and homogeneousthroughout and that will pass the rigorous inspection invariablygiven'to rifling bands such as are used on projectiles to act as a sealfor ordnance gases and to insure effective contact with the ,rifling ofa piece of ordnance.

In the drawing forming a part of this specification, Figure 1 is asection of mechanism for forming a tube with a closed end, and Fig. 2 isa detail view of the die part of Fig. 1 and illustrating-the tubeformed. Fig. 3 is a top view of the tube formed by the operation shownin Fig. 2. Figs..4, 5 and 6 illustratedrawing apparatus and the changesproduced in the tube by successive drawing operations. Fig. 7 is aperspective view of a band produced by this process.

The metal, which is preferably copper, is provided in a hot state. Themetal is first extrusion operation. Apparatus adapted for this purposeis illustrated in Fig. 1 consisting of a substantially cup-shaped die'10 placed in'a suitable die holder 11 and disably by molding, of a sizeand shape to fit closely within the lower part of the cup shaped recess15 in the die 10 which has a I) point.

1 preferably rounded bottom 18 and substantially vertical, cylindricalside walls 18 'of ably about the height indicated by dotted .lines inFig. 1. The side and bottom walls of the die merge gradually into oneanother so as to avoid all sharp corners past which the metal is to beforced and the consequent weakening or disruptingof the copper. Beforeplacing it in the die the copper block 16 is heated to a red heat,preferably within a few hundred degrees of its melting We have foundthat'good results may be obtained by heating the copper blocks 16 tofrom about 1500, to about 1600 F., but we are not to be confined to suchprecise temperatures, so long ,as the copper is not melted, and isheatedsufficiently to work readily in the extrusion operation to which it issubjected.

By means of the plunger 12 and head 13 the block of copper 16 issubjected to great pressure which may be as high as 25,000 to 30,000pounds per square inch. As the plunger 12 descendsfits head 13 engagesthe block of copper, the first efiect of its forcible engagementtherewith being to firmly settle the copper block 16 down in and give ita solid seat in the die recess 15,--forcibly bringing it into contactwiththe walls thereof both at the bottom and at the sides where-- by theblock of copper is firmly restrained The block of copper 16 fitting thusclosely within the recess 15 in the die, the material thereof isalw'ays,,,from the first contact of the head 18 therewith, subjected tovery great compressive force while being at all times restrained by thewalls of the die from lateral give or expansion, and the breaking, up ofthe grain or fiber or weakening of the strong coherent properties of thecopper, which results from the expansion thereof Without such forciblecompression or restraint, or from forcing blanks down into a die whichthey do not fit, is avoided.

As .the punch head 13 continues its descent the copper is extrudedfromthe die and is forced upward around the punch as is. clearly showninFig. 2, forming a tube 19 of which the interior diameter or bore issubstantially the greatest diameter of the punch 13, and the outerdiameter is substan- Y tially the diameter or bore of the uppersubstantially cylindrical surface 18 of the recess 15 in the die 10. Thepunch, die and copper block are preferably so proportioned that theupper end of the tube 19 so formed does not begin to emerge from the topof the die until that portion of the punch head 18 of greatest diameterhas entered within the die, so that during the act of extrusion thecopperv forming the sides of the tube is being forced directly upward,without lateral expansion, through the narrow annular opening betweenthe short, straight side portion 13 of thepunch head and the sides 18'of the recess 15 in the die and the tube is formed from a block whoseouter diameter .is substantially the same as the outer diameter of theextruded tube. \Vith the deep die provided with straight sides ofconsiderable height and with a rounded bottom merging smoothly into theside walls substantially as shown, and the punch with roundedsubstantially mushroom shaped head the copper may be made to flowwithout substantial disruption of its strong coherent structure, and itis to be noted that with punches and dies formed substantially as shownthe copper is forced through a passage decreasing substantiallyconstantly in s ze until it finally passes out the narrow annularopening at the top of the die and between the die and punch head. Byhandling the copper in this way and preventing expansion of the copperblock laterally, or in other words, away from the axis of the tube, andby making use of a block fitting substantially snugly within the lowerportion of the die and against the bottom and sides thereof, whereby itsshape need not be changed before the extrusion begins to take place, andby making use of the great compressive force exerted to effect theextrusion of the copper, we avoid all sponginess or lack of strongcoherent structure or opening of the grain of the metal or otherincipient defects which, while they may not be capable of detection inthe tube as extruded, may later develop into observable defects andweaknesses and even cause breakage in the tube when subsequently drawnand in the rings themselves.

At the limit of movement of the plunger head 13 suflicient material ispreferably left between the preferably rounded end 17 of the punch head13 and the correspondingly rounded bottom 18 of the die to form a closedend'20 for the tube 19 of a thickness sufficient to permit the use ofsuch closed end as a means whereby the tube may be manipulated insubsequent operations.

The straight sided portion 13 of the head 13 being relatively veryshort, the tube 19 may be readily stripped from the head 13 when thelatter is withdrawn from the die.

The tube thus formed being subjected to very great compressive forceduring its extrusion, and being formed from a block whose diameter issubstantially the same as that of the tube formed by the extrusionprocess, and which fits substantially closely against the sides andbottom of the die, whereby any unrestrained lateral expansion or otherchange of shape prior to extrusion and consequent weakening is avoided,is of strong, solid coherent structure throughout and is adapted forsubsequent treatment as by drawing operations, the character of thematerial of the tube so provided being such that subsequently no flaws,weakness or sponginess, such as would be inadmissible in copper riflingbands formed therefrom, are developed by the subsequent operation ofdrawing.

The tube shown in Figs. 2 and 3, after being stripped from the punch,can now be subjected to the required number of drawing steps, whereby itmay be given correct dimensions. In the drawing we show the tubeillustrated in Fig. 2 placed in the drawing die 22 (Fig. 1) and it ispushed through the die by reason of the drawing punch 23 having the end20 of the tube 19 to bear against. The die 22 and punch 23 are properlyproportioned to change the shape and thickness of .the tube, the formshown changing the tube 19 in Fig. 1- to the shape shown at 19 in Fig.5. If required, this tube 19 is pressed through the drawing die '24: bythe plunger 25 which bears on the end 20. The tubes are preferably drawncold. They may be pickled and annealed from time to time as before andbetween the steps of drawing.

These operations result-in the production of a tube which may havesubstantially the form shown at 19" in Fig. 6. Tubes of practically anydesired length may be obtained.

Having produced the tube 19" of the required diameter and thickness, thesaid tube can be cut 01f as at 26, such cuts resulting in the formationof bands as 27 shown in Fig. 7, the extreme end 26 of the drawn tube,which may be slightly imperfect and is generally more or less irregularin shape, being usually trimmed off and discarded. Such trimmed oif end26 and the bottom part 20 left after the rings are cut ofi", may, ofcourse, be remelted and used over so that no part of the expensivecopper is lost. Vith our improved process a very considerable economyresults from the fact that there is no need for rolling the copper as isrequired when bands are made from copper sheets and all scrap andtrimmings, which are greatly less than in the case of cutting blanksfrom rolled sheets, are immediately available for reuse on being simplymelted up. All of the operations of making bands according to ourimproved process may be very readily and inexpensively carried out,

Lemma the cost of thereby producing bands so perfect that the proportionof rejections on most rigid inspection is substantially negligible,being but a few cents per pound.

The compression, extrusion and drawing steps herein shown and describedclosely knit and compress all parts of the side walls of the tubes, andbands cut from such tube are of substantially uniformly good density andfirmness throughout, which is the most necessary qualification of thebands. While the tubes formed by extrusion as described are preferablycylindrical they may be of any cross-sectional form.

llaving thus described our invention, we claim:

1. The process of working copper which includes introducing into asubstantially cupshaped die, a heated copper block of substantially thesame shape as the die and fitting closely in the lower part thereof andextruding the copper from the die in the form of a tube.

2. The method of working copper which includes introducing a heatedcopper block into a die in which the block fits substantial] y closelyagainst the sides and bottom of the die and extruding the copper to forma tube by means of a punch having a lesser diameter than the diameter ofthe die and of the copper block fitting therein.

3. The method of working copper which includes introducing a heatedcopper block into a die provided with substantially cylin- (lrical sidesand a rounded bottom in the lower portion of which die the block fitsclosely, and extruding the copper to form a firmly coherent tube with aclosed end by means of a punch having a lesser diameter than thediameter of the die and block.

4. The process of working copper, which includes introducing into a diehaving its bottom walls merging gradually into its side walls, a heatedcopper block of substantially the same shape as the die and fittingsubstantially closely into the lower part thereof, and extruding thecopper from the die to form a strong coherent tube whose outer giameteris substantially the diameter of the 5. The process of making copperrifling bands, whichincludes introducing into a substantially cup-shapeddie, a heated copper block of substantially the same shape as the dieand fitting in the lower part thereof, extruding the copper from the diein the form of a tube, drawing the tube thus formed, and cutting it intorings.

6. The method of making copper rifiing bands which includes introducinga heated copper block into a die into and against the sides and bottomof which the block fits substantially closely and extruding the copperto form a tube by means of a punch having a lesser diameter than thediameter of the die and of the copper block fitting therein, drawing thetube so formed and cutting it into rings.

7. The method of making copper rifiing bands which includes introducinga heated copper block into a die provided with substantially cylindricalsides and a rounded bottom in the lower portion of which die the blockfits closely, and extruding the copper to form a firmly coherent tubewith a closed end by means of a punch having a lesser diameter than thediameter of the die and block, drawing the tube so formed by forceexerted against the closed end and cutting it into rings.

8. The process of making copper rifiing bands, which includesintroducing into a die having its bottom walls merging gradually intoits side walls a heated copper block of substantially the same shape asthe die, and.

fitting substantially closely into the lower part thereof, extruding thecopper from the die to form a strong coherent tube, whose outer diameteris the same as the diameter of the bore of the die, drawing the tube soformed, and cutting it into rings.

' In testimony that we claim the foregoing, we hereto set our hands,this 18th day of Sept, 1916.

FRED S. CARVER. W. H. HARMAN.

